Estimation of rotor speed of synchronous generators for small-signal stability assessment in power systems

Author(s)

Tatiane Cristina da Costa Fernandes

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2017-02-20

Examining board members

Rodrigo Andrade Ramos; Daniel Dotta; Francisco Damasceno Freitas; João Bosco Augusto London Junior; Rodrigo Hartstein Salim

• Advisor: Rodrigo Andrade Ramos

Abstract

In this thesis, an approach is proposed to estimate the rotor speed of synchronous generators connected to an electric power system (EPS), from signals that can be easily sampled by measuring equipment, such as current and voltage in high voltage side of the step-up transformer of the power plant. Accurate information about the dynamic behavior of system is essential for effective control and reliable operation of EPS, especially with the increasing complexity of the grid. Hence, the main aim of this work is to provide an estimate of the rotor speed signal that can be applied in the area of small-signal stability, in order to mitigate the detrimental effects of poorly damped electromechanical oscillations in EPSs. The developed approach is composed of two methods, where each of them is applicable depending on the characteristics of the problem to be solved and the available information. In the first method, a trajectory sensitivity technique is applied on the mismatch between the simulated output in the system linear model and the response of the real system. Using this error signal and the sensitivity curves, this method allows to identify and to calibrate some coefficients of the linear model and, consequently, to adequately describe the speed response of the generator under analysis. In this second method, a filtering technique is used, the Unscented Kalman Filter, which provides an adequate estimate for rotor speed even when high discrepancies are observed between the linear model and the sampled response of real system. The results obtained on test systems with different characteristics show the efficiency of the proposed approach. (AU)

• FAPESP's process: 11/22187-0 - An Aproach for the Application of Modal Estimation and Linear Model Identification in the Small-Signal Stability Analysis of Power Systems
• Grantee: Tatiane Cristina da Costa Fernandes
• Support Opportunities: Scholarships in Brazil - Doctorate